The present invention relates to a jig for Kelvin Test which is used in Kelvin Method, and adapted to be brought into elastic contact with a terminal provided on an electronic component to be tested thereby to test an electronic circuit or the like of the electronic component to be tested.
As one of methods for testing an electronic circuit or the like, there has been Kelvin Method. In performing this method, plungers 56, 56 of two probes 54, 54 are brought into elastic contact with a single terminal 52 which is provided on an electronic component 50 to be tested, as shown in FIG. 9. One of the probes 56 is used as a current supplying probe for supplying electric current to the terminal 52, having its other end contacted with an electric current supplying terminal 60. The other of the probes 56 is used as a voltage monitoring probe for monitoring electric voltage of the terminal 52, having its other end contacted with a voltage monitoring terminal 62. In the Kelvin Method, it is necessary to supply the electric current of a desired value to the terminal 52, and to keep the terminal 52 at a desired voltage.
Related arts to the probes 54, 54 which are favorably used in this Kelvin Method are disclosed in JP-A-2005-62100, JP-UM-A-03-122370, and JP-UM-A-61-48372. In any of the arts disclosed in these related arts, the two probes 54, 54 in pairs, namely, the current supplying probe and the voltage monitoring probe have the same size and shape.
In recent years, the terminal 52 which is provided on a circuit board on which the electronic circuit or the like is formed has become extremely small in shape. Moreover, in case where a plurality of the terminals 52, 52 are arranged, a pitch between the terminals has become extremely small. On the other hand, a large electric current must be supplied to the terminals 52, 52 . . . for test, in some cases. In case where the probes disclosed in the above described related arts are made compact in correspondence with the size of the terminals 52, 52 . . . which are provided on the electronic component 50 to be tested, when a large current is supplied for test, a large drop of electric voltage occurs in the current supplying probe 54, and a desired voltage cannot be maintained in the terminals 52, 52. This is because a sectional area of a tube of the probe 54 in a direction perpendicular to the axial direction is reduced in proportion to compactness of the probe, and its resistance value is increased, whereby a large drop of voltage occurs when a large current is supplied.